There is a variety of different packaging alternatives for processing, arranging, grouping, and packaging articles such as beverage containers, for instance the assembly of articles or containers into portable, relatively handy packaging units. Various possibilities are also known for assembling individual articles into larger bundles. Beverage containers, for instance, are mostly assembled and packaged by means of shrinking foil into bundles of four, six, or more containers. It is usually inevitable to produce bundles because they are the most common type of sales units for beverage containers or bottles of PET plastic material. To some extent, the bundles are further assembled and/or arranged together in layers and placed on pallets for transport purposes.
The manufacture of the known bundle types requires specific production steps in order to enable the commonly employed shrinking foils to be processed. These production steps require a relatively high energy input. The foil that is employed also entails costs for production, supply, handling, and subsequent waste disposal, as it is no longer needed after selling the packaged articles or bundles. The machinery for providing the so-called film wrapping modules and other handling stations also causes high investment costs. Finally, providing the so-called shrinking tunnels, where the bundles are wrapped in foil that is shrunk around the containers by hot air impingement, also requires a relatively high input of capital.
So-called strapped bundles represent a packaging variant, which generally makes it possible to dispense with the use of shrinking foils. For this variant, the containers are assembled to a bundle and joined together by means of so-called strapping bands. Strapping machines, which are operated either continuously or cyclically, are used for grouping containers, articles, or bottles into formations and then strapping them by means of strapping aggregates with a strapping band or with a plurality of strapping bands. Typical formations may be, for instance, 1×2 arrangements (two containers in a row), 2×2 arrangements (four containers in a square or in a rhomboid formation), 3×2, 4×3, or, generally, any variable n×m arrangement, as well. Owing to the undetermined arrangement of the containers relative to each other, however, the bundles possibly lack positional stability so that the use of such strapping bands may result in problems with stability. As a rule, the strapping bands will require certain pre-tension forces in order to reduce shifting of the containers.
The use of flexible articles and containers, such as plastic bottles that are used in the beverage industry, may, however, also cause problems as such bottles are subject to possible variations of the internal pressure inside the containers. Many beverage containers are impinged with carbon dioxide, nitrogen, or other gases or substances when being filled. The internal pressure of the containers intended for being strapped may vary in dependence on the temperatures during filling, on the outside or ambient temperature, on the solution concentration of the gas or of the carbon dioxide, on the time elapsed since the filling process, and on numerous other parameters, as the case may be, such as the temperature in the production hall, the temperature of the liquid to be filled into the containers, the season of the year, etc. However, as the parameters for strapping and the pre-tension forces to be applied for strapping need to be set to a specific value, a pre-tension that is either too high or too low may easily result. A pre-tension that is too high may cause damage to the containers, and a pre-tension that is too low may impair the stability of the bundles. Essentially, the only possibility to check if the selected strapping pre-tension has been properly set, is by taking samples and verifying them, which, however, results in producing reject containers and bundles. It takes a person to operate the strapping machine for adjusting and resetting the machine parameters.
A method for producing bundles from at least two articles that are joined together by means of a strapping tensed horizontally around the outsides of the articles is known from DE 10 2009 040 700 A1. This method involves a continuous conveying process for placing the strapping band around the articles and subsequently securing it. The articles are not stopped while the strapping is being applied, as the strapping is applied in a continuous process while the articles keep being conveyed. The strapping is thereby formed by at least one strap that is tensioned around the outer sides of the articles and subsequently connected under pre-tension at the ends.
The application heads employed for strapping the articles, bundles, or packaged goods are usually driven within machine frames and move one after the other over the bundles for applying the strapping bands. With the strapping bands needing to be permanently refed in this procedure, the high movement speeds of the application heads may result in problems regarding band refeeding, which may lead to machine malfunction under adverse conditions.